The Animal Models Core will provide technical support to Projects I, II and III to allow for the evaluation of various in vivo strategies for adeno-associated virus-based gene therapy for ornithine transcarbamylase deficiency (OTCD). The Gene Therapy Program at the University of Pennsylvania has extensive experience with the in vivo characterization of vectors in various murine models of OTCD. In the context of this P01 application, the Animal Models Core will provide full support at all levels of the in vivo gene transfer studies including study design; animal acquisition; breeding of OTC and FRG mice, management of in-life phase of studies including organization of the study, technical support for procedures and harvesting of samples; and necropsy. The Core will maintain four colonies that include the spf[ash], spf, OTC-KO and FRG mice to support the experimental needs of Projects I, II and III.